Conscription evasion or draft evasion is any successful attempt to elude a government-imposed obligation to serve in the military forces of one's nation. Sometimes draft evasion involves refusing to comply with the military draft laws of one's nation. Illegal draft evasion is said to have characterized every military conflict of the 20th and 21st centuries, in which at least one party of such conflict has enforced conscription. Such evasion is generally considered to be a criminal offense, and laws against it go back thousands of years.

Desertion is the abandonment of a military duty or post without permission and is done with the intention of not returning. This contrasts with unauthorized absence (UA) or absence without leave, which are temporary forms of absence.